Performance Characterization Of 3D Printing TC4 Titanium Alloy In Shear Test And Pin-type Bearing Test

3D printing technology had been developing rapidly in recent years,but there were still many deficiencies.Based on the lack of mechanical performance evaluation criteria of 3D printing titanium alloy,comparing with the difference between domestic and foreign relevant material test standard,this paper chooses shear test and pin-type bearing test as the method to perform 3D printing titanium alloy mechanical performance.Through the comparison of related test verification and data,the whole test scheme of 3D printing titanium alloy mechanical performance was designed,and the properties of 3D printed titanium alloy were measured and characterized by different analysis methods using these methods.At present,there is no national standard for shear test and pin-type bearing test.In view of this situation,a test framework suitable for 3D printing titanium alloy was established based on the characteristics of 3D printing titanium alloy materials.Test tools and test process were designed which would make targeted modification through the problems finding in the test process and test data.Shear test mainly focused on plate and material joints.There was no clear text method standard for the shear test of round bar specimens.Based on the shear test standard of aluminum alloy,this experiment designed the test scheme and test tools to study the shear test method of 3D printing TC4 titanium alloy.Pin-type bearing test was a kind of test method for the load of component parts by simulating the stress condition when bolt,pin,rivet and component were assembled.Due to 3D printing titanium alloy products had been widely applied to medical and aerospace fields,the test of pin-type bearing test characteristics of 3D printing TC4 titanium alloy was carried out research and analysis.Contrast tests were used to study the 3D printing titanium alloy pintype bearing test through specimen thickness,diameter and distance and edge distance in the test results.By analyzing and sorting out the experimental data,the mathematical relation was established,and the relations among the four parameters of sample thickness,edge distance,hole diameter and maximum load of pin-type bearing were clarified.The failure modes of the pin-type bearing test were analyzed.Three types of cracks which might be caused by pin-type bearing test were described,and the causes of the three types of cracks were analyzed and studied.In the pin-type bearing test of 3D printed Ti alloy,DIC method was introduced to study the process of piling and torsion in the test process,and the strain field diagram of the specimen was obtained.The test and analysis show that the piling over the bearing pin and the torsion of the specimen in the test are the main factors of the increase and instability of the test data.At the same time,DIC method was introduced in the pin-type bearing test to observe the deformation and tearing process of the specimens and obtained strain diagram of the specimens at different stages of the experiment.The deformation in the experiment was measured and analyzed by comparing the deformation images of the stable and unstable specimens.The formation process and causes of the crushing and the instability of the specimens occurred above the bearing pin were deduced from the images.DIC method could be used to have a direct understanding of the deformation and stress concentration area of the specimens in the pin-type bearing test,which was helpful for the in-depth analysis and research of the test.